I've got a file exported which in Quicktime, VLC etc shows up as 1:07:16 in duration. However the duration of the original timeline in FCP is 1:07:11. So there is a 5 second difference.
I didn't notice this issue and made an SRT subtitle file based on the version playing in Quicktime (1:07:16). I then converted that to XML and tried to import it into a new timeline with the original exported file, and of course the subtitles don't match up once you reach the end.
When the file is imported into FCP it shows up as 1:07:11, just like the original timeline.
Any ideas? I don't understand why the same file shows different durations in FCP and Quicktime...!
QTPlayer and VLC are just players and they are not necessarily for time counting.
FCP is a professional video application.
If your movie has a proper TC track, you should trust what FC is showing.